CN111410513B

CN111410513B - Thin microporous composite ceramic plate with high porosity and preparation method thereof

Info

Publication number: CN111410513B
Application number: CN202010313869.7A
Authority: CN
Inventors: 彭幸华; 吴进艺; 张谋森
Original assignee: Fujian Lopo Terracotta Panels Manufacturing
Current assignee: Fujian Lopo Terracotta Panels Manufacturing
Priority date: 2020-04-20
Filing date: 2020-04-20
Publication date: 2020-11-24
Anticipated expiration: 2040-04-20
Also published as: CN111410513A

Abstract

The invention discloses a composite ceramic plate with high porosity, which consists of a substrate layer, a transition layer and a nano metal particle surface layer, wherein the transition layer is a combined layer of the surface layer and the substrate layer and is used for forming a transition plane between a micro-bubble material and the metal particle surface layer, and the substrate layer structure contains combined closed pores with alternate large and small pores. The upper surface is adhered with a solidified metal coating, and the coating has the performances of antibiosis, bacteriostasis and photocatalytic degradation of organic pollutants. The ceramic plate is formed by secondary foaming and firing, and comprises a low-temperature pre-foaming stage and a medium-high temperature foaming stage; wherein the prefoaming is completed by a granular organic foaming agent, and the medium-high temperature foaming is completed by a compound inorganic foaming agent. The prepared composite ceramic plate has high closed porosity, low heat conductivity coefficient and low volume density, and the preparation method can effectively reduce the firing temperature and the firing time.

Description

Thin microporous composite ceramic plate with high porosity and preparation method thereof

Technical Field

The invention relates to the field of foamed composite ceramic plates, in particular to a high-porosity thin foamed composite ceramic plate with large pores and small pores and a preparation process thereof.

Background

The foamed ceramic is a cellular ceramic material which is produced by mixing solid phase and gas phase and is prepared by mixing clay, quartz and other inorganic raw materials with a foaming agent and grinding, pulverizing, molding, sintering and other processes. Due to the special properties of heat insulation, heat preservation, sound insulation, fire prevention, moisture prevention, light weight and the like, the composite material is widely applied to the fields of buildings and heat insulation and preservation. At present, various high-temperature foamed ceramic heat-insulating plates for external heat insulation of building external walls and heat insulation of roofs are gradually developed, but the current products still have the defects of poor heat-insulating effect, high water absorption rate, lack of decoration, incapability of directly replacing ceramic tiles and the like.

The existing preparation process of foamed ceramics also has a plurality of defects, such as high firing temperature, low pore-forming rate, connectivity of internal pores caused by high-temperature sintering and the like, and the problems of increased water absorption, freeze-thaw cycle and the like caused by the connected pores are easy to occur, so that the service life and the cold and heat shock resistance are further reduced. For example, CN104744070A discloses that a foamed ceramic heat-insulating plate is prepared at 1150-1200 ℃ by using fly ash as a main raw material and assisting with fly ash, bentonite, power plant slag, a foaming agent and the like, but has the defects of high water absorption rate and insufficient pore-forming rate of the product.

In the prior art, a series of researches on foamed ceramics and a preparation process thereof exist, which are listed as follows.

CN 110590332 discloses an environment-friendly heat-preservation decorative foamed ceramic plate, which is prepared by mixing and grinding 50-65% of stone waste, 10-16% of perlite waste, 10-18% of zeolite waste, 1-3% of phosphorite slag, 5-10% of argil waste, 0.1-0.5% of foaming agent, 1-3% of ferric oxide, 0.2-1% of grinding aid and 0.3-0.5% of ceramic body reinforcing agent in percentage by mass, then sequentially performing dry pressing molding, drying, firing at 1110 ℃ for 80-100 min, and naturally cooling.

CN 107459338 discloses a preparation method of a heat-insulating foaming material for waste ceramic-based building outer walls. The technical scheme is as follows: firstly, taking 65-80 wt% of waste ceramic powder, 5-15 wt% of aluminate cement, 5-15 wt% of clay and 5-15 wt% of red mud as raw materials, adding 0.1-0.3 wt% of water reducing agent and 150-400 wt% of water into the raw materials, and performing ball milling for 4-6 hours to obtain foaming slurry; mixing the foaming slurry and hexadecyl trimethyl ammonium bromide according to the mass ratio of 2500-3500 to 1, stirring for 2-5 min, casting, naturally drying for 24h, and drying at 80-150 ℃ for 12-24 h; and then preserving heat for 2-5 hours at 900-1100 ℃ to obtain the product.

CN 105036700 discloses a preparation process of a multicolor hollow ceramic plate, which is prepared from the following components in parts by weight of 1: 2:1, preparing a first ingredient, a second ingredient and a third ingredient; the prepared hollow ceramic plate has rich colors and bright colors.

CN 110372411A discloses preparation of a honeycomb-structure light-weight high-strength ceramic plate, which is prepared by adding various raw materials into a ball mill according to the following weight percentages: 4-15% of diopside, 15-65% of ceramic waste, 15-65% of marble waste, 15-65% of gold waste, 20-60% of solvent raw material, 10-45% of plastic clay, 15-30% of kaolin, pore-forming agent, debonding agent and water, wherein the water is added according to 50-60% of the total weight of the raw materials, the debonding agent is added according to 0.6-1% of the total weight of the raw materials, and when the fineness of slurry after ball milling reaches 0.1-0.5%, the high-strength ceramic plate with the honeycomb structure adopts a digital trueness to copy natural stone texture, the ceramic plate adopts a 3D ink-jet technology and is more three-dimensional and fine, harmful soluble salts mixed in the raw materials are filtered through a filter press, so that the stability of slurry is improved, and the quality.

CN 108238811 discloses a preparation method of a foamed ceramic plate, which comprises the following steps: 1) putting 90-95% of industrial solid waste raw materials and 5-10% of foaming materials into a feeder according to the weight percentage, and uniformly mixing, wherein the industrial solid waste raw materials are one or more of ceramic waste residues, waste ceramics, mine tailings and waste glass; the foaming material is a primary mineral or a crystalline compound containing crystal water; 2) putting the mixture into a ball mill, ball-crushing and screening the mixture by a screen; 3) sieving the powder particles by a sieving device, putting the powder particles into a slurry pool, adding water, stirring, soaking and aging; 4) storing the mixture in a powder bin after spray drying in a spray drying tower; 5) dry-laying the powder particles through a transfer cylinder, then carrying out tunnel drying, and then calcining and forming in a tunnel calcining kiln; 6) and naturally cooling, sorting, cutting and drying to obtain a finished product.

Although the prior art discloses a series of methods for preparing ceramic foam boards, one or more of the following drawbacks exist:

1) the product has low foaming degree and a large part of intercommunicating pores, so that the product has high heat conductivity coefficient and poor heat insulation effect;

2) lack of industry standard control of raw materials and quality: in the prior art, various tailings and factory ceramic wastes which are suitable for local conditions are generally used as main materials, so that although the cost can be reduced, the performance difference of the product is large along with the change of the quality of the raw materials, and the product with stable performance cannot be obtained, so that the industrial applicability is poor;

3) the research on the composite ceramic plate containing the foaming material is less, and the existing composite technology usually coats an adhesive on one surface of the foaming ceramic and pastes a decorative material layer to obtain a composite plate; or directly spreading the foaming material on the surface of the molding material such as ceramic tiles and the like for simple bonding or directly simply firing to obtain the composite board. Obviously, the bonding layer of the existing composite process is not tightly attached, the bonding strength is not enough, and the product is easy to age, so that the service life of the product is short and the building safety risk exists;

4) the existing foaming ceramic plate usually lacks a smooth surface, and the ceramic plate is further required to be attached with ceramic tiles or paint for grinding when being used for wall construction. Most of the foamed ceramic plates have rough surfaces, poor attractiveness and thick thickness (even more than 10cm), are usually only used as a middle heat insulation plate and cannot be directly used for indoor or outdoor wall decoration;

5) in the prior art, a few composite boards with smooth surfaces can be directly used for wall decoration, but the surface usually does not have antibacterial and other functions except poor interlayer bonding strength, and an antibacterial coating needs to be adopted, but the durability of the coating is poor, and the performance can be ensured only by frequent coating.

6) Finally, in the existing preparation process of the foamed ceramics, the firing temperature is over 1200 ℃, and the energy consumption is large. Obviously, the higher the firing temperature, the longer the firing time, and the higher the energy consumption. If the firing temperature is reduced by 100 ℃, the heat consumption of the unit product can be reduced by more than 10%.

Therefore, there is a need to develop a new composite ceramic plate and a process for preparing the same to overcome the above-mentioned disadvantages.

Disclosure of Invention

In order to overcome the defects in the prior art, the preparation method mainly solves the following technical problems for the preparation of the foamed ceramic plate;

1) the foamed ceramic plate material which has high porosity, lower normal-temperature heat conductivity coefficient, low volume density and compressive strength meeting the building requirements is provided;

2) the binding force between the composite layers of the composite ceramic plate is improved;

3) on the basis of ensuring the performance, the firing temperature and the firing time of the product are effectively reduced.

Therefore, the main objective of the present invention is to provide an integrally formed thin composite ceramic plate with high porosity and a method for preparing the same.

Specifically, in the first aspect, the invention provides a composite ceramic plate with high porosity, which is formed by integrally sintering a foaming base layer, a compact transition layer and a surface layer comprising titanium dioxide nano metal particles. The transition layer is a combined layer of the surface layer and the substrate layer and is used for forming a compact plane between the micro-bubble material and the metal particle surface layer. The foaming matrix layer contains combined closed air holes with alternate large and small holes caused by a composite foaming agent. The surface layer is a surface with antibacterial and photocatalytic performances, wherein a solidified metal coating is attached to the surface layer; the ceramic plate is attached to the wall surface, and then the surface does not need to be further subjected to antibacterial coating treatment, so that the ceramic plate has antibacterial and bacteriostatic properties and photocatalytic degradation performance of organic pollutants.

The ceramic plate is formed by secondary foaming and firing, and comprises a low-temperature pre-foaming stage and a medium-high temperature foaming stage; wherein the prefoaming is completed by a granular organic foaming agent, and the medium-high temperature foaming is completed by a compound inorganic foaming agent.

The base layer in the composite ceramic plate is prepared from the following raw materials:

argil, kaolin, potash feldspar, expanded perlite, quartz sand, diopside, bentonite, fluorite powder, a composite foaming agent, a foam fixing agent and an auxiliary agent; the auxiliary agent is a toughening agent and a dispersing agent.

Wherein, the composite foaming agent consists of an inorganic foaming agent and an organic foaming agent. Wherein the organic foaming agent is selected from organic high-efficiency pore-foaming agents which are insoluble in water and have a gas evolution quantity of not less than 100ml/g, and the preferred gas evolution quantity is not less than 150 ml/g.

Preferably, the organic blowing agent is azodicarbonamide powder, the powder being controlled to have a particle size of less than 10 microns, preferably those having a particle size finer than 1600 mesh, more preferably those finer than 2000 mesh. When in use, the azodicarbonamide powder can be directly suspended in water to prepare uniform suspension for use.

Wherein the inorganic foaming agent consists of silicon carbide and at least one metal carbonate, wherein the metal carbonate is selected from magnesium carbonate and lithium carbonate; wherein the mass ratio of the silicon carbide to the metal carbonate is 1-2: 1.

Further, the particle size of the inorganic foaming agent is not less than 600 meshes; for example, 600-900 mesh, preferably 600-800 mesh.

Wherein the toughening agent is selected from chopped glass fiber, preferably 10-50 μm in length.

Preferably, the ceramic plate substrate layer comprises the following raw material components in parts by weight:

40-50 parts of argil, 20-30 parts of kaolin, 20-25 parts of potash-soda feldspar, 15-20 parts of expanded perlite powder, 10-15 parts of diopside, 5-10 parts of quartz sand, 5-8 parts of bentonite, 1-3 parts of fluorite powder, 2-5 parts of an inorganic foaming agent, 2-5 parts of a foam stabilizer, 0.5-2 parts of azodicarbonamide, 1-2 parts of a chopped glass fiber toughening agent and 0.5-1 part of a dispersing agent.

Wherein the foam stabilizer is selected from borax and sodium phosphate; preferably borax; the dispersant is selected from polyvinyl alcohol or hydroxyethyl cellulose.

Alternatively, the fluorite powder as the flux may be replaced with fluorite tailings powder.

Wherein, the pottery clay preferably contains 60-70 wt% of silicon dioxide, 10-20 wt% of aluminum oxide, 3-10 wt% of ferric oxide and other main components, and the loss on ignition is less than 5%.

Wherein the mass ratio of potassium oxide to sodium oxide in the potash albite is not less than 2: 1. preferably, the potassium albite is one having a preferred silica content of not less than 60 wt%, potassium oxide content of not less than 10 wt%, and alumina content of not less than 10 wt%.

Optionally, the matrix layer may also include ceramic waste, preferably not more than 30 wt%.

In the composite ceramic plate, the main raw materials for preparing the transition layer adopt the same components and proportions of the substrate layer so as to ensure the consistency of the physicochemical properties of the bonding parts, ensure the consistency of the sintering properties of the powder of the substrate layer and the transition layer of the ceramic plate and reduce the difference of the physical properties between the sintered ceramic plate layers.

Specifically, the main raw materials for preparing the transition layer adopt argil, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and flexibilizer raw materials which have the same proportion and amount as the matrix layer.

Wherein the transition layer does not contain the foaming agent component in the matrix layer to form a dense surface structure with higher hardness.

In the composite ceramic plate, the main raw materials for preparing the surface layer of the nano metal particles are nano titanium dioxide, nano zinc oxide and nano silicon dioxide. The nano titanium dioxide and the nano zinc oxide are dispersed among silicon dioxide particles, and are stably bonded to the surface of the ceramic plate through high-temperature fusion sintering between the silicon dioxide and the transition layer material, the interlayer bonding strength is high, and compared with coating construction in a coating form, the sintering bonding has longer stability and firmer bonding property.

In a second aspect, the invention also provides a low-temperature firing process of the composite ceramic plate, wherein the low-temperature firing process comprises a multi-stage foaming process.

Specifically, based on the composite foaming agent of the present invention, uniform foaming can be performed several times during firing: at the temperature of 190-250 ℃, the organic foaming agent particles are heated and decomposed to generate a microporous structure, so as to form primary porous; the clearance of the inorganic particles is dredged in the range of 600-950 ℃ to continuously form a porous structure; at 900 deg.C or 950 deg.C, the components of alkali metal and alkaline earth metal oxide are melted to produce liquid phase, and the inorganic foaming agent is decomposed to produce gas under the action of liquid phase viscous resistance, so that large closed pores are formed.

Therefore, the foaming agent prepared by combining the organic pore-foaming agent and the composite inorganic foaming agent can generate foaming at about 200 ℃, and the defects of interfore fusion and low closed pore rate caused by concentrated foaming are avoided by adjusting the proportion of foaming components and controlling the temperature rise process, so that the thermal performance such as low water absorption, heat preservation, heat insulation and the like is realized.

The heating rate in the firing process of the present invention is preferably in a gradient manner. It is to be noted that the content of the foaming component is such that if the amount of the foaming component is too large, the bubbles are likely to burst and overflow, or small bubbles are combined to increase the number of interconnected pores, and the water absorption becomes large.

Specifically, based on meeting the specific requirements, the low-temperature firing process of the composite ceramic plate specifically comprises the following steps (1) to (3):

step (1): preparing a ceramic slab serving as a substrate layer (namely, a substrate ceramic blank) and carrying out low-temperature pre-foaming treatment:

s1-1: mixing raw material powder components of pottery clay, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and a foam stabilizer uniformly according to a proportion, grinding to obtain mixed raw material powder, sieving, adding a glass fiber toughening agent and an inorganic foaming agent component, and mixing uniformly to obtain matrix ceramic blank raw material powder. And adding a dispersing agent and an organic foaming agent azodicarbonamide into water to form a uniform suspension to obtain a solvent material.

S1-2: mixing the base greenware raw material powder with a solvent material to obtain base greenware slurry; and granulating the slurry through spray drying to obtain blank powder particles, drying, carrying out ageing treatment, carrying out dry pressing forming to obtain a matrix ceramic blank, and drying in a drying kiln.

S1-3: and (3) conveying the dried blank into a heat treatment kiln for gradient temperature rise, and carrying out pre-foaming treatment at the temperature range of 190-250 ℃ to obtain the pre-foamed substrate ceramic blank.

The temperature of the prefoaming is dependent on the thermal decomposition temperature of the organic blowing agent used.

Step (2): compounding a transition layer and performing high-temperature steam treatment:

s2-1: uniformly mixing raw material powder components of argil, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as the matrix greenware, grinding and sieving the raw material powder components, and adding a toughening aid to obtain transition layer raw material powder; adding the dispersing agent into a proper amount of water to obtain a solvent material. And uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, and ageing for later use.

S2-2: coating the transition layer slurry on one surface of the pre-foamed substrate ceramic blank, standing at 50-60 ℃ to dry and solidify the transition layer slurry, thereby forming a smooth transition layer.

S2-3: carrying out steam curing treatment on the substrate ceramic blank coated with the transition layer by using high-temperature steam at the temperature of 120-150 ℃ to promote the junction surface of the transition layer and the ceramic blank to be further combined in a penetration manner; taking out the green body, drying and obtaining the greenware body containing the surface of the transition layer.

And (3): coating a surface layer and sintering and forming:

s3-1: adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion liquid; then sequentially adding titanium dioxide, zinc oxide and silicon dioxide nano particles with the particle size of 10-50nm into the dispersion liquid, and adjusting the pH to 9 by using strong ammonia water to obtain the nano titanium dioxide-based composite metal particle suspension.

S3-2: spraying the nano titanium dioxide-based particle suspension on the surface of the dried greenware transition layer to form a nano metal surface layer; and (3) drying after spraying to obtain a composite ceramic body coated with a nano metal surface layer, and performing gradient fast firing on the dried composite ceramic body in a roller kiln to obtain a finished product of the composite microporous ceramic plate with high porosity.

Specifically, the specific flow of each step is as follows:

step (1): preparing a ceramic slab as a substrate layer (i.e., substrate greenware)

S1: ingredients

1) The preparation method comprises the steps of uniformly mixing raw material powder components of pottery clay, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and a foam stabilizer according to a proportion, grinding or ball milling by using a grinding machine to obtain mixed raw material powder, sieving by using a 250-mesh sieve and a 300-mesh sieve, adding a glass fiber toughening agent and an inorganic foaming agent component with the granularity of 600-mesh and 800-mesh into the mixed powder, and uniformly mixing in a stirrer to obtain matrix ceramic blank raw material powder.

2) Adding the dispersing agent and the azodicarbonamide particles into a proper amount of water, heating to 30-45 ℃ at normal temperature or slightly, keeping the temperature and stirring for 5-10min to form uniform suspension, and cooling to room temperature to obtain a solvent material.

S2: blank making

1) Stirring and mixing the matrix greenware raw material powder and the solvent material in a uniform suspension state to obtain matrix greenware slurry; spray drying and granulating the slurry by a spray drying tower to obtain blank powder particles; drying the granules until the water content is about 10%, and then carrying out aging treatment for one day for later use.

Wherein, the weight of the solvent material is controlled to be 1 to 1.5 times, preferably 1 to 1.2 times of the weight of the matrix greenware raw material powder when preparing the matrix greenware slurry.

2) And (3) carrying out dry pressing molding on the blank powder particles after spray drying by using a blank making mold and a dry pressing molding machine to obtain a ceramic plate blank serving as a substrate layer, namely a substrate ceramic blank, wherein the blank size can be as follows: the length is 30-35cm, the width is 20-25cm, and the thickness is 0.5-4 cm.

3) And demolding the molded green body, and fully drying and drying in a drying kiln at a drying temperature not higher than 150 ℃, preferably not higher than 130 ℃.

Wherein, the particle size of the spray powder is controlled between 60 meshes and 120 meshes so as to obtain better comprehensive performance of the finished product.

S3: pre-foaming treatment: sending the dried blank into a heat treatment kiln for low-temperature pre-foaming treatment of gradient temperature rise, wherein the pre-foaming treatment process is as follows:

1) first, a preheating treatment is performed: heating to 150-; then heating to 190 ℃ at the heating rate of 2-3 ℃/min, and preserving heat for 15-20 min;

2) pre-foaming treatment of an organic foaming agent; after preheating treatment, slowly heating from 190 ℃ to 250 ℃ at the heating rate of 0.5-1 ℃/min, and preserving heat for 45-60min to uniformly heat and decompose the organic foaming agent;

3) cooling treatment: and after pre-foaming treatment, cooling to 50 ℃ at a cooling rate of 2-3 ℃/min, and discharging to obtain a pre-foamed matrix ceramic blank.

Step (2): compounding transition layer and high temperature steam treatment

S1: preparing materials: uniformly mixing raw material powder components of argil, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as those in the matrix greenware, grinding, sieving with a 400-mesh and 500-mesh sieve, adding a toughening aid into the mixed powder, and uniformly mixing in a stirrer to obtain transition layer raw material powder; adding the dispersing agent into a proper amount of water, properly heating and stirring the mixture to be uniform, and cooling the mixture to room temperature to obtain a solvent material.

Uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, controlling the specific gravity of the slurry to be 1.5-1.8(g/ml), and ageing for 24 hours for later use.

S2: uniformly and flatly applying the slurry of the transition layer on one surface of the pre-foamed substrate greenware, marking the surface as an upper surface, standing for 4-6h at 50-60 ℃, and drying and curing the slurry of the transition layer to form a smooth transition layer; the thickness of the transition layer can be 3-30% of the thickness of the base ceramic blank, preferably 5-20%

For example, it is preferred that the transition layer has a thickness of 1cm or less, e.g. 0.5-5 mm; more preferably 1-3 mm.

Wherein the slurry is uniformly distributed on the surface of the greenware by methods including, but not limited to, slurry distribution methods such as slurry spraying, slurry rolling, slurry brushing and the like. And adding the diluted slurry into a stirring barrel of a high-pressure spray gun, and uniformly spraying the slurry on the surface of the dried greenware body in an atomizing mode.

Alternatively, the paddle may also be carried out by means of a glazing tool.

S3: steam treatment: carrying out steam curing treatment on the substrate greenware on the surface of the distributed transition layer for 3-5min by using high-temperature steam with the temperature of 120-150 ℃ to promote the transition layer material to be further combined with the greenware combined surface in a penetration manner under the temperature and the pressure; and taking out the green body, drying and drying to obtain the greenware body containing the surface of the transition layer.

Wherein the steam treatment can be carried out in a high-temperature steam chamber or by a steam spray gun; the spray distance is maintained when a steam spray gun is employed to avoid compromising the smoothness and integrity of the transition layer surface.

Compared with the method that the transition layer is directly soaked by water, the method can quickly enable the water vapor to enter the interface gap of the transition layer material for wetting by adopting high-temperature steam, and the integrity of the interface of the transition layer cannot be damaged.

And (3): coating a surface layer and sintering and forming:

s1: preparing a nano titanium dioxide based composite metal particle suspension:

adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion liquid with the mass concentration of 0.1-0.3 wt%; and then sequentially adding titanium dioxide, zinc oxide and silicon dioxide nanoparticles with the particle size of 10-50nm into the dispersion liquid, uniformly stirring, and adjusting the pH to 9 by using strong ammonia water to obtain the nano titanium dioxide-based composite metal particle suspension.

Wherein the concentration of the nano titanium dioxide, the nano zinc oxide and the nano silicon dioxide in the solution is 5-10 wt%, 3-5 wt% and 10-15 wt% in sequence.

Preferably, the total solids content of the suspension is controlled not to exceed 30 wt%.

S2: sprayed metal surface layer

Uniformly spraying the nano titanium dioxide-based particle suspension on the surface of the dried greenware transition layer by a high-pressure spray gun in an atomizing mode at the temperature of 50-60 ℃ to form a uniform nano metal surface layer; and after spraying, placing the ceramic powder in a drying kiln for drying or drying by hot air to obtain a composite ceramic body coated with a nano metal surface layer, and preparing the composite ceramic body for firing in a next roller kiln.

Wherein the thickness of the metal surface layer is controlled to be 0.1-10 microns, preferably less than 1 micron.

Preferably, the suspension is sprayed in an amount of 50 to 300 g/m.

Alternatively, the titanium dioxide-based composite particles can be coated on the surface of the smooth ceramic blank transition layer by brushing.

In the invention, the adopted metal materials are high-temperature resistant materials with high melting points, so that the structure cannot be damaged due to melting in the firing process, and meanwhile, the metal materials can be stably embedded into the surface of the ceramic plate in the firing process.

S3: gradient sintering and forming, which comprises the following specific operations:

1) heating the dried composite ceramic blank to a preheating region of 600-700 ℃ at the speed of 5-10 ℃/min in a roller kiln, and carrying out preheating and heat preservation for 0.5 hour; heating to 900-950 ℃ oxidation region at the speed of 3-5 ℃/min, and carrying out oxidation and heat preservation for 1 hour;

2) high-temperature foaming: continuously heating to a high-temperature foaming region of 1000-1050 ℃ at the heating rate of 5 ℃/min, and carrying out heat preservation foaming for 1.5-2 h;

3) gradient cooling: cooling to 500-600 ℃ at the cooling rate of 8-10 ℃/min, and preserving heat for 0.5-1 h; and then continuously cooling at a slow cooling rate of 3-5 ℃/min until the ceramic plate is discharged, naturally cooling after the ceramic plate is discharged, and edging and packaging to obtain a finished product of the thin microporous composite ceramic plate with high porosity.

For the performance test of the composite ceramic plate, the water absorption rate and the porosity are determined according to GB/T1996 'porous ceramic apparent porosity and capacity test method'; measuring the thermal conductivity coefficient of the heat conduction instrument; the bending strength is measured according to GB/T1996 'method for testing the bending strength of porous ceramics'.

The integral density of the thin composite ceramic plate prepared by the invention is not more than 1.0g/cm³The volume density of the foaming matrix part is less than 0.8g/cm³The foam material has high foaming rate (the porosity is more than 50 percent) and combined pore characteristics, and the diameters of pores are both mm and below (the distribution range of the diameters of macropores is less than 2mm, and the diameters of micropores are less than 1 mm); has a low thermal conductivity of 0.03-0.05W/(MK), and a water absorption (V/V) of less than 0.5%; the compression strength of the matrix layer is not lower than 15MPa, and the fire-proof grade is A1 grade, which accords with the regulations of civil building external thermal insulation system and external wall decoration fire-proof (2009 (46)).

The thickness of the thin composite ceramic plate prepared by the invention is generally less than 40mm, preferably less than 20mm, more preferably less than 15mm, and the actual thickness can be determined according to actual needs.

In a third aspect, the invention provides the use of the composite ceramic plate as a heat-insulating or bacteriostatic decorative material and for attaching to a building wall surface.

The thin composite ceramic plate prepared by the invention has a foaming surface and a smooth antibacterial surface, and realizes the decoration and heat preservation integrated function with uniform decoration effect and excellent physical performance; the composite material has the characteristics of high hardness, high porosity and low density, can be directly used for building external wall surfaces as heat insulation ceramic boards, and can also be used for indoor wall surface decoration (such as toilets, kitchens and the like) to achieve the purposes of water resistance, flame retardance and antibiosis. When the foaming agent is used for wall surface attaching construction, the foaming lower surface can be compacted and attached to the thermal insulation mortar of the building wall body without further attaching decoration such as ceramic tiles or spraying paint. In addition, the composite ceramic plate can also be used as a sound insulation material for sound insulation wall surfaces.

The beneficial effects of the invention include but are not limited to the following aspects:

(1) the invention innovatively adopts the water-insoluble high-yield organic pore-forming agent in the form of suspension liquid to participate in low-temperature firing pore-forming. Wherein the organic pore-forming agent is not mixed with the solid particle raw material but is pre-dispersed in water and then dispersed in the raw material particle base material in the form of suspension during pulping, thereby facilitating the formation of uniformly distributed pore sources. In the pre-foaming stage, the pore-forming agent begins to slowly decompose and react to release gas, and a plurality of independent small pore units are formed and distributed in the greenware, namely the micropore type in the honeycomb structure, and the average diameter is less than 1 mm.

The invention innovatively adopts a gradient combined foaming process. In the high-temperature sintering stage, the organic pore-forming agent is completely decomposed, at the moment, the inorganic pore-forming agent is decomposed to release gas, the inorganic pore-forming agent is an inorganic material with larger particles, the diameter of formed pores is larger, a large amount of high-temperature viscous glass phase substances exist in the blank, and the pores are sealed in the blank after cooling, so that a larger pore type with the level of 1-2mm in the honeycomb structure is formed. And the micropores which are not easy to break are filled in the solid spaces among the macropores, so that the number of the air holes is greatly increased, the volume density of the ceramic plate is reduced, and the heat insulation performance is improved.

In addition, the invention carries out pre-foaming treatment before formal high-temperature firing, and then coats a transition layer and a surface layer, thereby being beneficial to filling rough surfaces caused by micro bubbles and greatly avoiding the defect of surface flatness reduction caused by direct firing.

(2) At present, in the prior art, a foaming method of a single foaming agent is basically adopted, and the narrow decomposition temperature range easily causes air hole combination. The foaming agent prepared by combining the organic pore-foaming agent and the composite inorganic foaming agent can continuously foam at the temperature of more than 200 ℃, and the closed porous body ceramic plate with the composite pore structure and high closed pore rate can be formed by adjusting the proportion of foaming components and controlling the temperature rise process, so that the ceramic plate has good thermal properties of low water absorption, heat preservation, heat insulation and the like.

The composite pore-forming agent combined by organic and inorganic materials can form closed pores with the combination of large and small pores, obviously improve the pore-forming rate even under the firing condition of low temperature (about 1000 ℃), and overcome the defects of low pore-forming rate and large pore diameter caused by adopting a single inorganic pore-forming agent in the prior art. And the micropores formed by the organic pore-forming agent can effectively fill the material solid spaces among the macropores, thereby further enhancing the heat preservation and insulation effect of the finished product and meeting the requirements of wall decoration application.

(3) The preparation method of the invention has the highest firing temperature of less than 1100 ℃, belongs to medium-high firing, avoids micropore damage caused by material melting in high-temperature firing at 1200 ℃ or above 1300 ℃, can form a honeycomb-like structure with high porosity, and greatly reduces energy consumption. In addition, the firing method adopts the modes of low-temperature firing and multi-gradient foaming, so that the ceramic material cannot crack or deform in the firing process of the ceramic tile due to sudden temperature change.

(4) The raw materials selected by the ceramic plate preparation method are basically low-cost mineral raw materials, the cost is low, the quality standard is uniform and easy to control, the adopted firing process equipment is consistent with the production of the traditional roller kiln, and the industrial production is easy to realize; the components of the blank and the plane material of the transition layer are consistent, the compatibility difference does not exist at the joint of the base layer and the transition layer, the expansion and contraction properties are basically consistent during firing, and the finished product of the blank is not deformed or cracked.

Meanwhile, the invention adopts thin ceramic materials, so compared with foamed ceramics (the thickness is generally about 10cm or more) used for partition boards, the invention also has the advantages of difficult cracking and short firing time.

(5) In the method, the foamed ceramic matrix, the binding layer and the metal surface layer are formed and then subjected to steam treatment and high-temperature sintering, wherein the components of the matrix and the binding layer are contacted and permeated under the action of high temperature so as to be tightly fused and combined, and the defect of insufficient bonding strength of the composite ceramic plate in the prior art is overcome.

(6) The pottery plate prepared by the invention contains different components with high and low melting points by reasonably setting the contents of components such as pottery clay, chopped fiber auxiliary agent and the like in the main ingredients, can form a liquid phase in a wider temperature range, and improves the micropore proportion. On the basis of good heat insulation performance, low thermal conductivity (lower than 0.08W/(m.K), low volume density and high compressive strength, the sintering temperature can be reduced, the hardness and toughness of the ceramic plate are improved, and the generation of defective products such as cracking and the like in the firing process is avoided.

(7) The composite metal particles are sprayed on the surface of the ceramic plate prepared by the invention, and are solidified and embedded on the surface after high-temperature sintering, so that the surface of the ceramic plate has antibacterial and photocatalytic properties, which are caused by the antibacterial self-cleaning property of the nano titanium dioxide and the zinc oxide on the surface, and the effects of inhibiting bacteria and degrading organic pollutants are achieved; in addition, the smooth surface has the self-cleaning capability similar to that of a ceramic tile, and the appearance texture of the ceramic board is effectively improved.

Drawings

FIG. 1 is a partial view of a foaming structure of a ceramic plate according to example 3 of the present invention; the right drawing is a partial view of the foamed structure of the ceramic plate of comparative example 1 according to the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The following detailed description of preferred embodiments of the invention and the examples included therein will make it easier to understand the context of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Preparation example 1

Preparation of Pre-foamed base greenware 1

1) Selecting raw material powder according to the following parts by weight:

50 parts of argil, 20 parts of kaolin, 20 parts of potash-sodalite, 15 parts of expanded perlite powder, 10 parts of diopside, 5 parts of quartz sand, 5 parts of bentonite, 1 part of fluorite powder, 4.5 parts of inorganic foaming agent consisting of silicon carbide, lithium carbonate and magnesium carbonate in equal weight ratio, 2 parts of borax, 1.5 parts of azodicarbonamide, 1.5 parts of 30-50 mu m chopped glass fiber and 0.5 part of polyvinyl alcohol. Wherein, the potash albite contains about 65 to 66 weight percent of silicon dioxide, about 12.5 to 13 weight percent of potassium oxide and about 4.5 to 5.0 weight percent of sodium oxide.

2) The preparation method comprises the steps of uniformly mixing the raw material powder components of argil, kaolin, potash-sodalite, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and borax according to the proportion, grinding by using a grinder to obtain mixed raw material powder, sieving by using a 300-mesh sieve, adding a glass fiber toughening agent and an inorganic foaming agent component which is sieved by using a 600-mesh sieve into the mixed powder, and uniformly mixing in a stirrer to obtain about 132kg of matrix greenware raw material powder.

Adding the prepared dispersant hydroxyethyl cellulose and azodicarbonamide particles which are sieved by a 1800-mesh sieve into water, slightly heating and stirring for 10min to form uniform suspension, cooling to room temperature to obtain a solvent material for later use, and stirring again for heavy suspension when in use.

3) Stirring and mixing the base greenware raw material powder and a solvent material in a uniform suspension state to obtain base greenware slurry weighing about 289 kg; spray drying and granulating the obtained slurry by a spray drying tower to obtain blank powder particles of 80-100 meshes, drying the particles until the water content is about 10%, and then aging for one day. And carrying out dry pressing forming on the aged granular materials by using a dry pressing forming machine under the pressure of 45MPa to obtain a ceramic plate blank serving as a substrate layer, namely a substrate ceramic blank body, wherein the size of the blank body is 35cm in length, 25cm in width and 1.5cm in thickness.

And demolding the molded blank, fully drying and drying the molded blank in a drying kiln, and setting the drying temperature to be 120-125 ℃.

4) Pre-foaming treatment:

sending the dried blank into a heat treatment kiln for low-temperature pre-foaming treatment of gradient temperature rise, wherein the pre-foaming treatment process is as follows:

4-1) heating to 150 ℃ at the heating rate of 7-8 ℃/min, and keeping the temperature for 15 min; then heating to 190 ℃ at the heating rate of 2 ℃/min, and preserving heat for 20 min.

4-2) after preheating treatment, slowly heating from 190 ℃ to 250 ℃ at the heating rate of 1 ℃/min, and preserving heat for 60min to uniformly heat and decompose the organic foaming agent.

4-3) pre-foaming, cooling to 50 ℃ at a cooling rate of 2 ℃/min, and discharging to obtain a pre-foamed substrate ceramic blank.

Preparation example 2

Preparation of Pre-foamed base greenware 2

1) Selecting raw material powder according to the following parts by weight:

45 parts of argil, 25 parts of kaolin, 20 parts of potash-sodalite, 16 parts of expanded perlite powder, 12 parts of diopside, 7 parts of quartz sand, 6 parts of bentonite, 2 parts of fluorite powder, 4 parts of inorganic foaming agent consisting of silicon carbide and magnesium carbonate in equal weight ratio, 2 parts of borax, 1 part of azodicarbonamide, 1 part of 20-50 mu m chopped glass fiber and 0.5 part of polyvinyl alcohol dispersing agent. Wherein, the parameters of the potash albite are the same as those of the preparation example.

2) The preparation method comprises the steps of uniformly mixing the raw material powder components of argil, kaolin, potash-sodalite, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and borax according to the proportion, grinding by using a grinder to obtain mixed raw material powder, sieving by using a 300-mesh sieve, adding a glass fiber toughening agent and an inorganic foaming agent component sieved by using 700 meshes into the mixed powder, and uniformly mixing in a stirrer to obtain the matrix greenware raw material powder of about 140 kg. Adding dispersant polyvinyl alcohol and azodicarbonamide particles (same as above) into water, stirring for 10min to form uniform suspension, cooling to room temperature to obtain solvent material, and stirring again when in use.

3) Stirring and mixing the base body greenware raw material powder and a solvent material in a uniform suspension state to obtain base body greenware slurry weighing about 310 kg; spray drying and granulating the obtained slurry by a spray drying tower to obtain blank powder particles of 80-100 meshes, drying the particles, and aging for one day. And (3) carrying out dry pressing on the aged granular materials in a blank forming mold by using a dry pressing forming machine to obtain a matrix ceramic blank body, wherein the size of the blank body is 30cm in length, 25cm in width and 18mm in thickness. And demolding the molded blank, fully drying and drying the molded blank in a drying kiln, and setting the drying temperature to be 120-125 ℃.

4) Pre-foaming treatment:

4-1) heating to 160 ℃ at the heating rate of 8 ℃/min, and keeping the temperature for 15 min; then heating to 190 ℃ at the heating rate of 3 ℃/min, and preserving heat for 20 min.

Preparation example 3

Preparation of Pre-foamed base greenware 3

1) Selecting raw material powder according to the following parts by weight:

50 parts of argil, 30 parts of kaolin, 25 parts of potash-sodalite, 20 parts of expanded perlite powder, 15 parts of diopside, 10 parts of quartz sand, 8 parts of bentonite, 3 parts of fluorite powder, 4 parts of inorganic foaming agent consisting of silicon carbide and lithium carbonate in equal weight ratio, 2 parts of borax, 1 part of azodicarbonamide, 1 part of 30-50 mu m chopped glass fiber and 0.8 part of polyvinyl alcohol dispersing agent. Wherein the potassium albite parameters are the same as above.

2) The preparation method comprises the steps of uniformly mixing the raw material powder components of argil, kaolin, potash-sodalite, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and borax according to the proportion, grinding by using a grinder to obtain mixed raw material powder, sieving by using a 300-mesh sieve, adding a glass fiber toughening agent and an inorganic foaming agent component which is sieved by using a 600-mesh sieve into the mixed powder, and uniformly mixing in a stirrer to obtain about 168kg of matrix greenware raw material powder. Adding dispersant polyvinyl alcohol and azodicarbonamide particles (with the same granularity) into water, stirring for 10min to form uniform suspension, cooling to room temperature to obtain solvent material, and stirring again when in use.

3) Stirring and mixing the base greenware raw material powder and a solvent material in a uniform suspension state to obtain base greenware slurry weighing about 370 kg; spray drying and granulating the obtained slurry by a spray drying tower to obtain blank powder particles of 80-100 meshes, drying the particles, and aging for one day. And (3) carrying out dry pressing molding on the aged granular materials in a blank forming mold by using a dry pressing molding machine to obtain a matrix ceramic blank body, wherein the size of the blank body is the same as that of the base ceramic blank body. And demolding the molded blank, fully drying and drying the molded blank in a drying kiln, and setting the drying temperature to be 125-130 ℃.

4) Pre-foaming treatment:

4-1) heating to 160 ℃ at the heating rate of 8 ℃/min, and keeping the temperature for 10 min; then heating to 190 ℃ at the heating rate of 2 ℃/min, and preserving heat for 15 min.

4-2) after preheating treatment, slowly heating from 190 ℃ to 250 ℃ at the heating rate of 1 ℃/min, and preserving heat for 45min to uniformly heat and decompose the organic foaming agent.

Example 1

1) Mixing raw material powder components of pottery clay, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as those in the base ceramic blank prepared in the preparation example 1 uniformly, grinding and sieving by a 400-mesh sieve, adding a glass fiber toughening agent into the mixed powder, and mixing uniformly in a stirrer to obtain about 13kg of transition layer raw material powder; the dispersant was added to water, heated slightly and stirred until homogeneous, and cooled to room temperature to give a solvent mass. Uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, controlling the specific gravity of the slurry to be 1.5-1.6g/ml, and ageing for 24 hours for later use.

2) Coating the transition layer slurry on the surface of the greenware matrix in a blank making mould until the thickness is 2mm, leveling the surface of the transition layer and marking as the upper surface, standing for 4-6h at 50-60 ℃ to dry and solidify the transition layer slurry, thereby forming a smooth transition layer.

3) Carrying out steam curing treatment on the substrate ceramic blank containing the surface of the transition layer in a steam chamber for 5min by using high-temperature steam at the temperature of 120-; and taking out the green body, drying and drying to obtain the greenware body containing the surface of the transition layer.

3) Preparing nano titanium dioxide based composite metal particle suspension: adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion liquid with the mass concentration of 0.2 wt%; and then sequentially adding titanium dioxide with the particle size of 10-30nm, zinc oxide and silicon dioxide nanoparticles with the particle size of 20-30nm into the dispersion liquid, uniformly stirring, and adjusting the pH to 9 by using strong ammonia water to obtain a nano titanium dioxide-based composite metal particle suspension, wherein the concentrations of the nano titanium dioxide, the nano zinc oxide and the nano silicon dioxide in the solution are sequentially 8.5 wt%, 4 wt% and 12 wt%.

4) Uniformly spraying the nano titanium dioxide-based particle suspension on the surface of a dried greenware transition layer by using a high-pressure spray gun at the temperature of 50 ℃ in an amount of 150-; and after spraying, placing the ceramic body in a drying kiln for drying or drying by hot air to obtain the composite ceramic body coated with the nano metal surface layer.

5) Carrying out gradient sintering molding on the composite ceramic body according to the following flow:

5-1) heating the dried composite greenware to a preheating interval of 600 ℃ at the speed of 5 ℃/min in a roller kiln, and carrying out preheating and heat preservation for 0.5 hour; then heating to the oxidation region of 900-950 ℃ at the speed of 5 ℃/min, and carrying out oxidation and heat preservation for 1 hour;

5-2) high-temperature foaming: continuously heating to a high-temperature foaming interval of 1000 ℃ at the heating rate of 5 ℃/min, and carrying out heat preservation foaming for 2 h;

5-3) gradient cooling: cooling to 600 ℃ at a cooling rate of 8 ℃/min, and keeping the temperature for 0.5 h; and then continuously cooling at a slow cooling rate of 3-5 ℃/min until the ceramic plate is discharged, naturally cooling after the ceramic plate is discharged, and grinding to obtain a thin composite microporous ceramic plate finished product with the thickness of about 28-30 mm.

Referring to GB/T1996 porous ceramic apparent porosity and capacity test method and porous ceramic bending strength test method, the parameters of the obtained ceramic plate microporous matrix are as follows: the total porosity of the composite pores is 65-65.5%, the diameter distribution range of the macropores is 1-2mm, and the diameter distribution range of the micropores is 0.1-0.5 mm; the bulk density is 0.49-0.50g/cm³The compressive strength is 16.85MPa, the heat conductivity coefficient is 0.035-0.036W/(MK), and the water absorption rate is 0.3%; the fire rating is a1 rating.

Example 2

1) Mixing raw material powder components of pottery clay, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as those in the base ceramic blank prepared in the preparation example 2 uniformly, grinding and sieving by a 400-mesh sieve, adding a glass fiber toughening agent into the mixed powder, and mixing uniformly in a stirrer to obtain about 14kg of transition layer raw material powder; the dispersant was added to water, heated slightly and stirred until homogeneous, and cooled to room temperature to give a solvent mass. And uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, wherein the specific gravity of the slurry is 1.55g/ml, and the transition layer slurry is aged for 24 hours for later use.

2) In a blank making mold, uniformly spraying the transition layer slurry on the surface of the ceramic body by using a high-pressure spray gun until the thickness is 3mm, treating the surface of the transition layer to be smooth, and standing at 50-60 ℃ to dry and solidify the transition layer slurry.

3) Carrying out steam treatment on the surface of the matrix greenware transition layer by using high-temperature steam with the temperature of 120-130 ℃ by using a steam spray gun so as to further permeate and combine the transition layer material with the greenware combination surface under the temperature and the pressure; and drying to obtain a greenware body containing the surface of the transition layer.

3) Adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion liquid with the mass concentration of 0.3 wt%; and then sequentially adding titanium dioxide with the concentration of 10-30nm, zinc oxide and silicon dioxide nanoparticles with the concentration of 20-30nm into the dispersion liquid, uniformly stirring, and adjusting the pH to 9 by using strong ammonia water to obtain a nano titanium dioxide-based composite metal particle suspension, wherein the concentrations of the nano titanium dioxide, the nano zinc oxide and the nano silicon dioxide in the solution are 10 wt%, 5 wt% and 10 wt% in sequence.

4) Uniformly spraying the nano titanium dioxide-based particle suspension on the surface of the dried greenware transition layer by using a high-pressure spray gun at the temperature of 50 ℃ in an amount of 150 g/square meter to form a uniform nano metal surface layer; and after spraying, placing the ceramic body in a drying kiln for drying or drying by hot air to obtain the composite ceramic body coated with the nano metal surface layer.

5-1) heating the dried composite greenware to a preheating interval of 500 ℃ at the speed of 6-8 ℃/min in a roller kiln, and carrying out preheating and heat preservation for 0.5 hour; then heating to the oxidation region of 900-950 ℃ at the speed of 5 ℃/min, and carrying out oxidation and heat preservation for 1 hour;

5-2) high-temperature foaming: continuously heating to a high-temperature foaming region of 1000-1020 ℃ at the heating rate of 5 ℃/min, and carrying out heat preservation foaming for 1.5 h;

5-3) gradient cooling: cooling to 600 ℃ at a cooling rate of 8 ℃/min, and keeping the temperature for 0.5 h; and then continuously cooling at a slow cooling rate of 3-5 ℃/min until the ceramic plate is discharged, naturally cooling after the ceramic plate is discharged, and grinding to obtain a finished product of the thin composite microporous ceramic plate.

The parameters of the microporous matrix of the obtained ceramic plate are as follows: the total porosity of the composite pores is 59.5-60%, the diameter distribution range of macropores is 1-2mm, and the diameter distribution range of micropores is 0.1-0.5 mm; the volume density is 0.56-0.57g/cm³The compressive strength is 18.45MPa, the heat conductivity coefficient is 0.041-0.042W/(MK), and the water absorption rate is 0.3%; the fire rating is a1 rating.

Example 3

1) Uniformly mixing raw material powder components of argil, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as those in the matrix ceramic blank prepared in the preparation example 3, grinding and sieving by a 500-mesh sieve, adding a glass fiber toughening agent into the mixed powder, and uniformly mixing in a stirrer to obtain about 17kg of transition layer raw material powder; the dispersant was added to water, heated slightly and stirred until homogeneous, and cooled to room temperature to give a solvent mass. And uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, wherein the specific gravity of the slurry is 1.72g/ml, and the transition layer slurry is aged for 24 hours for later use.

2) Coating the transition layer slurry on the surface of the ceramic body until the thickness is 3-4mm, treating the surface of the transition layer to be smooth, and standing at 50-60 ℃ to dry and solidify the transition layer slurry.

3) Performing steam treatment on the surface of the substrate greenware transition layer in a high-pressure steam chamber by using high-temperature steam with the temperature of 140-150 ℃ for 4-5min to further enable the transition layer material to be combined with the greenware combination surface in a penetration manner under the temperature and pressure; and drying to obtain a greenware body containing the surface of the transition layer.

3) Adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion liquid with the mass concentration of 0.3 wt%; then, titanium dioxide, zinc oxide and silicon dioxide nanoparticles with the particle size of 10-30nm are sequentially added into the dispersion liquid, the mixture is uniformly stirred, the pH value is adjusted to 9 by using strong ammonia water, and a nano titanium dioxide-based composite metal particle suspension is obtained, wherein the concentration of the nano titanium dioxide, the nano zinc oxide and the nano silicon dioxide in the solution is the same as that in the embodiment 2.

4) Uniformly spraying the nano titanium dioxide-based particle suspension on the surface of the dried greenware transition layer by using a high-pressure spray gun at the temperature of 50 ℃ in an amount of 150-160 g/sq.m to form a uniform nano metal surface layer; and after spraying, placing the ceramic body in a drying kiln for drying or drying by hot air to obtain the composite ceramic body coated with the nano metal surface layer.

5-1) heating the dried composite greenware to a preheating interval of 500 ℃ at the speed of 8-10 ℃/min in a roller kiln, and carrying out preheating and heat preservation for 0.5 hour; then heating to the oxidation region of 900-950 ℃ at the speed of 5 ℃/min, and carrying out oxidation and heat preservation for 1 hour;

5-2) high-temperature foaming: continuously heating to a high-temperature foaming region of 1030 ℃ and 1050 ℃ at the heating rate of 5 ℃/min, and carrying out heat preservation foaming for 1.5 h;

5-3) gradient cooling: cooling to 600 ℃ at a cooling rate of 8 ℃/min, and keeping the temperature for 0.5 h; and then continuously cooling at the cooling rate of 5 ℃/min until the ceramic plate is discharged, naturally cooling after the ceramic plate is discharged, and grinding to obtain a finished product of the thin composite microporous ceramic plate.

The parameters of the obtained ceramic plate are as follows: the total porosity of the composite pores is 55.5-56%, the diameter distribution range of the macropores is 1-2mm, and the diameter distribution range of the micropores is 0.1-0.5 mm; the bulk density is 0.62-0.63g/cm3, the compressive strength is 19.80MPa, the heat conductivity is 0.045-0.046W/(MK), and the water absorption is 0.4%; the fire rating is a1 rating.

Comparative example 1

A composite microporous ceramic plate control 1 was prepared under the conditions of example 3, except that the foaming temperature of the roller kiln was increased to 1150 ℃ and that the azodicarbonyl raw material as an organic foaming agent was not contained. The parameters of the obtained reference ceramic plate microporous matrix are as follows: no composite pores appear, the porosity is 37-38%, the pore diameter distribution range is 1-3mm, the number of uneven pores is more, and the pore diameter is larger; the volume density is 0.96-0.97g/cm³The heat conductivity coefficient is 0.09-0.1W/(MK), and the water absorption rate is 1.5%; the compressive strength is 16.80 MPa.

As can be seen from the structure shown in fig. 1, the microporous ceramic plate substrate sample (left drawing) in example 3 has a composite pore structure with alternating large pores and small pores, and the composite pores have high roundness and good sealing property, and are basically closed pores, the average pore diameter of the large pores is 1-1.5mm, and the average pore diameter of the micropores is significantly smaller than 0.5 mm. In contrast, the ceramic plate substrate (right drawing) in comparative example 1 has only large pores, and the formed pores are not uniform, and even collapse and filling phenomena occur after the materials are melted at high temperature.

Comparative example 2

Composite microporous ceramic plate control 2 was prepared as in example 3, except that the water-insoluble organic blowing agent, azodicarbonyl, was replaced with equal mass of water-soluble ammonium bicarbonate, and the remaining conditions were unchanged. The parameters of the obtained reference ceramic plate microporous matrix are as follows: no composite pores appear, the total porosity is 36-37%, the pore diameter distribution range is 2-4mm, the number of uneven pores is more, and the pore diameter is larger; the volume density is 0.75-0.76g/cm³The thermal conductivity coefficient is 0.12W/(MK), and the water absorption rate is 1.7%; the compressive strength is 7.7 MPa.

It is worth mentioning that the parameters of the ceramic plate substrate in this comparative example are substantially the same as those in comparative example 1, but the compressive strength is greatly reduced. The reasons may be as follows: because ammonium bicarbonate is water soluble, it is very water soluble. Even if the inorganic filler is not dissolved in water in advance, the inorganic filler is completely dissolved in the slurry during stirring pulping and exists in the material in a molecular form. Because the ammonium bicarbonate is low in thermal decomposition temperature, the ammonium bicarbonate is completely decomposed in the early stage of rapid heating and firing, however, the ammonium bicarbonate in a single molecular state is decomposed by heating and cannot generate bubbles visible to the naked eye, and instead, the blank is filled with gaseous molecules to become loose in structure expansion, so that the compressive strength is greatly reduced. Therefore, the water-soluble organic pore-forming agent cannot generate micropores and fill in the spaces between the macropores, is not suitable for use as a ceramic plate foaming agent, and has a negative effect.

In addition, as can be seen from the above examples, after the granular azodicarbonamide is added, the compressive strength of each product of the invention is still greater than the requirement of 13MPa of the national standard (GB/T4741). Therefore, although ammonium carbonate organic pore-forming agent substances can reduce the volume density of the product, the strength performance of the product is reduced, and therefore, proper organic pore-forming agents should be adopted in combination with the formula and the actual requirement.

Comparative example 3

A composite microporous ceramic plate control 3 was prepared according to the conditions of example 3, except that the high-temperature foaming temperature of the roller kiln in step 5) of example 3 was increased to 1300 ℃. The observation shows that the composite pores mainly exist in a macroporous form, the microporosity is greatly reduced, and the open pores are obviously increased. The parameters of the obtained reference ceramic plate microporous matrix are as follows: the porosity is 45-46%, and the distribution range of the diameters of macropores is mainly 2-5 mm; the bulk density is 0.36-0.37g/cm³The thermal conductivity coefficient is 0.076W/(MK), and the water absorption rate is 2.4%.

As can be seen from the above comparative examples, the ceramic sheet product of the present invention has a large pore diameter, a low bulk density and a high water absorption as the firing temperature increases. The thermal conductivity increases. When the firing temperature is low, the pores of the foam are generally small and closed. The reason for this may be: the reaction of the foaming agent, particularly SiC, is insufficient at low-temperature firing, and the pores of the foam are small. At temperatures above 1100 deg.C, the pore size becomes larger and the distribution becomes broader, probably because the melt viscosity gradually decreases with increasing temperature, more liquid phase is generated, and part of the microbubbles and small bubbles merge with each other to form large bubbles, resulting in larger pore size of the pores and in part of the bubbles collapsing. Although high-temperature firing brings the advantages of low volume density, reduced self-mass and the like, low closed porosity and low water absorption rate brought by low-temperature firing are more beneficial to heat insulation and water resistance. Therefore, in order to avoid the damage of the micro-bubble structure generated by the organic pore-foaming agent, the sintering temperature of the invention is controlled within 1100 ℃.

Although the present invention has been described in detail by referring to the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A preparation method of a microporous composite ceramic plate with high porosity comprises a low-temperature pre-foaming stage and a medium-high temperature foaming stage; the method is characterized by comprising the following specific steps:

step (1): preparing a base layer ceramic plate blank and carrying out low-temperature pre-foaming treatment:

s1-1: mixing raw material powder components of pottery clay, kaolin, potash-sodalite, expanded perlite powder, diopside, quartz sand, bentonite, fluorite powder and a foam stabilizer uniformly according to a proportion, grinding to obtain mixed raw material powder, sieving, adding a chopped glass fiber toughening agent and an inorganic foaming agent component, and mixing uniformly to obtain matrix ceramic blank raw material powder; adding a dispersing agent and azodicarbonamide particles serving as an organic foaming agent into water to form uniform suspension to obtain a solvent material; wherein the inorganic foaming agent consists of silicon carbide and at least one metal carbonate;

wherein the raw materials comprise the following components in parts by weight: 40-50 parts of argil, 20-30 parts of kaolin, 20-25 parts of potash-soda feldspar, 15-20 parts of expanded perlite powder, 10-15 parts of diopside, 5-10 parts of quartz sand, 5-8 parts of bentonite, 1-3 parts of fluorite powder, 2-5 parts of a foam stabilizer, 2-5 parts of an inorganic foaming agent, 1-2 parts of a chopped glass fiber toughening agent, 0.5-2 parts of azodicarbonamide and 0.5-1 part of a dispersing agent;

s1-2: mixing the base greenware raw material powder with a solvent material to obtain base greenware slurry; performing spray drying granulation on the slurry to obtain blank powder particles of 60-120 meshes, drying, ageing, performing dry pressing to form a base body layer ceramic plate blank, and drying;

s1-3: sending the dried blank into a heat treatment kiln for gradient temperature rise, and carrying out pre-foaming treatment in a temperature range of 190-;

s2-1: uniformly mixing raw material powder components of argil, kaolin, potash feldspar, expanded perlite powder, diopside, quartz sand, bentonite and fluorite powder in the same proportion as the raw materials for preparing the ceramic plate blank with the substrate layer, grinding and sieving the raw material powder components, and adding a toughening aid to obtain raw material powder of the transition layer; adding a dispersing agent into a proper amount of water to obtain a solvent material, uniformly stirring and mixing the transition layer raw material powder and the solvent material to obtain transition layer slurry, and carrying out aging treatment for later use;

s2-2: uniformly coating the transition layer slurry on one surface of the pre-foamed substrate ceramic blank, standing at 50-60 ℃ to dry and solidify the transition layer slurry, thereby forming a smooth transition layer; performing steam treatment by using 120-temperature and 150-DEG C high-temperature steam to promote the transition layer to be further combined with the greenware joint surface in a penetration manner, taking out the greenware body, drying and drying to obtain a greenware body containing the transition layer surface;

and (3): coating a surface layer and sintering and forming:

s3-1: adding a polymethacrylic acid ammonium dispersant into water to prepare a dispersion solution, then sequentially adding titanium dioxide, zinc oxide and silicon dioxide nanoparticles of 10-50nm into the dispersion solution, and adjusting the pH to 9 by using strong ammonia water to obtain a nano titanium dioxide-based composite metal particle suspension;

s3-2: and spraying the nano titanium dioxide-based particle suspension on the surface of the dried greenware transition layer to form a nano metal surface layer, drying to obtain a composite greenware body coated with the nano metal surface layer, and firing the dried composite greenware body in a roller kiln by adopting a gradient heating process to obtain the microporous composite greenware plate with high porosity.

2. The method according to claim 1, wherein the pre-foaming treatment in step (1) is performed by the following steps:

1) preheating treatment: heating to 150-; then heating to 190 ℃ at the heating rate of 2-3 ℃/min, and preserving heat for 15-20 min;

2) pre-foaming treatment; after preheating treatment, slowly heating from 190 ℃ to 250 ℃ at the heating rate of 0.5-1 ℃/min, and preserving heat for 45-60min to uniformly heat and decompose the organic foaming agent;

3. The method of claim 1, wherein the thickness of the transition layer in step (2) is 3-30% of the thickness of the base greenware; the steam treatment is carried out in a high-temperature steam chamber or by means of a steam lance.

4. The method according to claim 1, wherein the concentration of the nano titanium dioxide, the zinc oxide and the silicon dioxide in the composite metal particle suspension obtained in the step (3) is 5-10 wt%, 3-5 wt% and 10-15 wt% in sequence; the thickness of the metal surface layer is controlled below 1 μm.

5. The method according to claim 1, wherein the step (3) of sintering by a gradient temperature rise process is specifically performed as follows:

3) gradient cooling: cooling to 500-600 ℃ at the cooling rate of 8-10 ℃/min, and preserving heat for 0.5-1 h; and then continuously cooling at a slow cooling rate of 3-5 ℃/min until the ceramic plate is discharged, naturally cooling after the ceramic plate is discharged, and grinding the edge to obtain a finished product of the composite ceramic plate.

6. Composite ceramic board produced according to any one of claims 1 to 5, characterised in that the resulting ceramic board has a foamed matrix layer bulk density of less than 0.8g/cm³The porosity is more than 50%, and the thermal conductivity is lower than 0.05W/(mk).

7. Use of the composite ceramic panel according to claim 6 in the construction of wall surfaces.